Valve Actuator is mounted on the valves and moves the specific valve to a definite direction in response to a signal using an external power source. There are various types of valve actuators such as:

• Manual Valve Actuator: These do not require an external power source. They use a lever for this purpose of driving gears.
• Electric Actuator: These use a single phase or a three phase Alternate current or Direct Current motor. This is mainly used for the purpose of driving a series of gears to achieve the desired torque level.
• Pneumatic Valve Actuator: These convert the air pressure to linear or rotary motion and change the position of the respective valve.
• Hydraulic Actuator: These also convert the fluid pressure supply into linear or rotary motion and change the position of the valve to the desired level.

There are two main things which are to be taken into account while considering these actuators. These are the valve motion and the style of operation of these actuators. There are again types of motion valves such as the Rotary valve, Linear valves, etc.

The operating styles of an actuator are also of two kinds like the motion valves. These are the specific devices that limit the motion of the actuator to desired levels. Some rotary devices move a right angle or through various angles according to desired levels.

Valve Actuator has to possess some general specifications like voltage, supply pressure, the diameter of the stem of the valve, location type and mode, operating temperature while using the valve actuator, control signal type of input, etc. The devices that use alternate current or direct current are also easily available.

Different fail safe methods are present for such actuators. In instances of power failure the devices can open or close the valves. Sometimes the locations in which these actuators are going to be used also play an important part in their make and composition. Potentially risky environment will call for a safety measure equipped actuator whilst other potentially safer places may call for usage of the more common kind of actuator.